This invention relates to AC switching magnets in general and more particularly to an improved shorting ring for such magnets.
In AC switching magnets such as those used in airbrake contactors and the like, the magnetic pole is formed of a plurality of laminations which are generally riveted together. The end face of the pole contains a channel into which a shorting ring may be inserted. (For background as to the use of such shorting rings see U.S. Pat. No. 2,546,740). One conventional means of securing the shorting ring within the slot is that shown in German Offenlegungsschrift 1,764,522. As illustrated therein the shorting ring contains on each end a connecting strap which is bent down toward the magnet to hold the shorting ring in place after a brief elastic deformation during assembly. The straps at the end will contain indentations which will fit into either tabs bent out from the cover sheet of the pole piece or the rivets which hold the laminations together. With this sort of connection, particularly if the rivet is not centered, the shorting ring can move a small amount relative to the pole piece and will do so during each switching cycle of the magnet. This leads to wear of the mounting means i.e., the tabs or rivet end, and results in an undefined position of the shorting ring or the engagement point for the mounting. In addition some prior attachment arrangements, such as that shown in German Offenlegungsshrift 1,464,217, require attachment over a large area thereby increasing the torsion on the joint.